Recently, scanner systems have been widely employed in the printing field. Various light sources have been put to practical use in recording devices for forming images by scanner systems.
In particular, laser rays having an oscillation wavelength of from 620 to 690nm are advantageously employed. Of these, a He--Ne laser (having an oscillation wavelength of 633nm) and a semiconductor laser (having an oscillation wavelength of about 670nm or so) have been popularized, as being excellent in the stability and the ability of forming high-quality images. Since each point on the photographic material to be subjected to scanning exposure is exposed for a short period of time of from 10.sup.-7 to 10.sup.-3 seconds, the material is needed to be highly sensitive even to such short-time exposure to be able to form an image having a high contrast.
Photographic materials which are highly sensitive to at least two or more laser rays having an oscillation wavelength of from 620 to 690nm (preferably, a He--Ne laser ray (633nm and a semiconductor layer ray (670nm.+-.10nm)) are very advantageous, since one and the same material of these can be applied to at least two or more recording devices having the corresponding light sources. Therefore, the development of such photographic materials has been desired.
For instance, JP-A-3-59637 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") discloses a rapidly-processable photographic material to be exposed to a He--Ne light source, which contains a carbocyanine or rhodacyanine spectral sensitizing dye and in which the amount of gelatin in the emulsion layer and that in the protective layer are specifically controlled.
However, since carbocyanine dyes have a narrow spectral sensitivity distribution, it is difficult to provide a photographic material which contains such a carbocyanine dye and which is highly sensitive to two or more lasers each having a different oscillation wavelength range.
On the other hand, rhodacyanine dyes have a broader color sensitivity distribution than carbocyanine dyes but are still unsatisfactory.
U.S. Pat. No. 5,116,722 discloses a silver halide photographic material containing a particular tri-nuclear merocyanine spectral sensitizing dye, which is exposed to a light source having a wavelength range of from 600 to 690nm.
However, the material disclosed in said U.S. patent specification, though having a relatively broad spectral sensitivity, is not sufficiently satisfactory in its sensitivity and residual color due to the spectral sensitizing dye after processing the material.
All of these conventional photographic materials are not satisfactory in that, when the amounts of the replenishers to the processing solutions are reduced in processing the materials or when the materials are processed rapidly, residual color is increased.
Given the situations, the development of a high-sensitivity silver halide photographic material, which has a broad and gentle spectral sensitivity distribution within a wavelength range of from 620 to 690nm and which yield little residual color after processed, has been strongly desired.